Add a dialog service to retrieve current weather conditions

[tonysurma]

(originally created by @toolboc)

In times of natural disaster, weather can be a significant factor and extremely useful piece of information when planning movement in or around an affected area.

Using any available free weather service, provide information to the user in the bot welcome message found in RootDialog.cs within SendWelcomeMessage.

Keep in mind that you will want to use an entry in the resources*.resx files to ensure that users of various languages can make use of this information. For this, you may also want to add a key in web.config to specify the locale to retrieve weather for.

The particular requirements are a bit open-ended but you will need to consider that the service works for all supported languages.